Are aged domains untouchable?

I found a low comp keyword where every site has a 15 to 20 yo domain, with the exception of the top ranking website which is 3 yo.

Not a single website has the keyword in its name.

They are mostly review type sites.

Any thoughts?

IMHO that is because era of EMDs is behind us. When it comes if it's beatable competition or not, that's up to you to find out. For example, amazon has pretty old domain, can you beat it at SERP - yes you can.

Build a network of high quality web2.0. I have about 60 of them. About 20 are EMDs. Then 40 PBN sites. About half are partial match and half brand names. I drain some of the PBN juice through the web2.0. And always do creative, smart and competent keyword research. When you lock in on niches go all the way and never stop. Google likes slow, natural, blackhat SEO. I also transcribe from old library books and do high quality manually spun articles to fluff out my content.